View source for OpenSSL

{{Short description|Implementation of SSL and TLS protocols}}
{{Distinguish|OpenSSH}}
{{Use mdy dates|date=October 2020}}
{{Infobox software
| name = OpenSSL
| logo = OpenSSL logo.svg
| screenshot = UEFI Secure Boot DB certificate.png
| caption = <code>openssl</code> showing a [[X.509]] certificate for [[UEFI]] [[UEFI#Secure Boot|Secure Boot]]
| developer = The OpenSSL Project
| released = {{start date and age|1998}}
| latest release version = {{Multiple releases
  | branch1 = Stable
  | version1 = {{wikidata|property|preferred|references|edit|Q1052790|P348|P548=Q2804309}}
  | date1 = {{start date and age|{{wikidata|qualifier|preferred|single|Q1052790|P348|P548=Q2804309|P577}}}}
  | branch2 = LTS
  | version2 = {{wikidata|property|preferred|references|edit|Q1052790|P348|P548=Q15726348}}
  | date2 = {{start date and age|{{wikidata|qualifier|preferred|single|Q1052790|P348|P548=Q15726348|P577}}}}
}}
| latest preview version = {{wikidata|property|preferred|references|edit|Q1052790|P348|P548=Q51930650}}
| latest preview date = {{start date and age|{{wikidata|qualifier|preferred|single|Q1052790|P348|P548=Q51930650|P577}}}}
| operating system = <!--Nothing; it is a library, not a full app-->
| programming language = [[C (programming language)|C]], [[Assembly language|Assembly]], [[Perl]]
| genre = [[Cryptography]] [[Library (computer science)|library]]
| license = 3.0 and later: [[Apache License|Apache-2.0]]<ref>{{Cite web|title=/source/license.html|url=https://www.openssl.org/source/license.html|access-date=2021-03-03|website=www.openssl.org|archive-date=January 18, 2019|archive-url=https://web.archive.org/web/20190118094240/https://www.openssl.org/source/license.html|url-status=live}}</ref><br />1.x and earlier: OpenSSL<ref>{{Cite web|url=https://spdx.org/licenses/OpenSSL.html|title=OpenSSL License &#124; Software Package Data Exchange (SPDX)|website=spdx.org}}</ref>
| website = {{URL|www.openssl.org/}}
}}

'''OpenSSL''' is a software [[library (computing)|library]] for applications that provide secure communications over [[computer network]]s against eavesdropping, and identify the party at the other end. It is widely used by [[Internet]] [[server (computing)|servers]], including the majority of [[HTTPS]] [[website]]s.

OpenSSL contains an [[open-source software|open-source]] implementation of the [[Transport Layer Security|SSL and TLS]] protocols.  The core [[library (computer science)|library]], written in the [[C (programming language)|C programming language]], implements basic [[cryptography|cryptographic]] functions and provides various utility functions. Wrappers allowing the use of the OpenSSL library in a variety of computer languages are available.

The OpenSSL Software Foundation (OSF) represents the OpenSSL project in most legal capacities including contributor license agreements, managing donations, and so on. OpenSSL Software Services (OSS) also represents the OpenSSL project for support contracts.

OpenSSL is available for most [[Unix-like]] [[operating system]]s (including [[Linux]], [[macOS]], and [[BSD]]), [[Microsoft Windows]] and [[OpenVMS]].

== Project history ==

The OpenSSL project was founded in 1998 to provide a free set of encryption tools for the code used on the Internet. It is based on a fork of [[SSLeay]] by Eric Andrew Young and Tim Hudson, which unofficially ended development on December 17, 1998, when Young and Hudson both went to work for [[RSA Security]].  The initial founding members were Mark Cox, Ralf Engelschall, Stephen Henson, [[Ben Laurie]], and Paul Sutton.<ref>{{Cite mailing list |url=https://marc.info/?l=ssl-users&m=91566086807308&w=2 |title=Announce: OpenSSL (Take 2) |access-date=2018-10-29 |mailing-list=ssl-users |first=Ben |last=Laurie |date=1999-01-06 |archive-date=March 23, 2019 |archive-url=https://web.archive.org/web/20190323042441/https://marc.info/?l=ssl-users&m=91566086807308&w=2 |url-status=live}}</ref>

In 2018 OpenSSL [[version numbering]] skipped from 1.1.1 to 3.0.0, omitting 2 as a major version number to avoid a conflict with one of OpenSSL's modules. Version 3.0.0 was the first to use the [[Apache License]].

{{As of|2019|May}},<ref name=new_omc_member>{{cite web |title=New Committers |url=https://openssl-library.org/post/2019-05-20-committers/ |publisher=OpenSSL Software Foundation |date=2019-05-20 |access-date=2024-10-11 |archive-date=October 14, 2024 |archive-url=https://web.archive.org/web/20241014060544/https://openssl-library.org/post/2019-05-20-committers/ |url-status=live}}</ref> the OpenSSL management committee consisted of seven people<ref name=omc>{{cite web|title=OpenSSL Management Committee|url=https://www.openssl.org/community/omc.html|publisher=OpenSSL Software Foundation|access-date=2019-11-03|archive-date=July 22, 2018|archive-url=https://web.archive.org/web/20180722125659/https://www.openssl.org/community/omc.html|url-status=live}}</ref> and there are seventeen developers<ref name=committers>{{cite web|title=OpenSSL Committers|url=https://www.openssl.org/community/committers.html|publisher=OpenSSL Software Foundation|access-date=2019-11-03|archive-date=July 22, 2018|archive-url=https://web.archive.org/web/20180722125724/https://www.openssl.org/community/committers.html|url-status=live}}</ref> with commit access (many of whom are also part of the OpenSSL management committee). There were only two full-time employees (fellows) and the remainder were volunteers.

By 2024, there were fourteen employees.

The project had a total income of US$5.5&nbsp;million in 2024.<ref>{{cite web|title=OpenSSL Annual Report 2024|url=https://openssl-corporation.org/about/Annual-Report-2024.pdf}}</ref> Development of TLS 1.3 was sponsored by [[Akamai Technologies|Akamai]].<ref>{{cite mailing list |title=Akamai sponsors TLS 1.3 |url=https://mta.openssl.org/pipermail/openssl-announce/2017-January/000090.html |mailing-list=openssl-announce |date=2017-01-19 |first=Steve |last=Marquess |access-date=2018-11-09 |archive-date=February 1, 2017 |archive-url=https://web.archive.org/web/20170201174938/https://mta.openssl.org/pipermail/openssl-announce/2017-January/000090.html |url-status=live}}</ref>

== Major version releases ==

<!--Template:Version - for version & release history. Documentation & examples: http://en.wikipedia.org/wiki/Template:Version-->
{|class="wikitable" style="min-width:40%"
|+ OpenSSL release history<ref name=changelog>{{cite web|title=OpenSSL – Changelog|url=https://www.openssl.org/news/changelog.html|publisher=OpenSSL Software Foundation|access-date=2016-09-26|archive-date=September 13, 2016|archive-url=https://web.archive.org/web/20160913103335/https://www.openssl.org/news/changelog.html|url-status=live}}</ref><ref name=NEWS.md>{{cite web |url=https://github.com/openssl/openssl/blob/master/NEWS.md |title=OpenSSL Releases |website=[[GitHub]] |access-date=2022-12-06}}</ref>
|-
! Version !! Original release date !! Support until<ref name=releasestrat>{{cite web|title=OpenSSL Library – Release Strategy|url=https://openssl-library.org/policies/releasestrat/|publisher=OpenSSL Software Foundation|access-date=2024-08-01|archive-date=December 9, 2024|archive-url=https://web.archive.org/web/20241209175142/https://openssl-library.org/policies/releasestrat/|url-status=live}}</ref> !! Comment !! Last minor version
|-
| {{Version |o |0.9.1}}<ref name=openssl_0.9.x_notes>{{cite web |url=https://github.com/openssl/openssl/blob/master/NEWS.md#openssl-09x |title=OpenSSL 0.9.x series notes |website=[[GitHub]] |access-date=2022-12-06}}</ref>
| {{start date|1998|12|23|df=yes}}
|
| align="right" |
* Official start of the OpenSSL project
| 0.9.1c (23 December 1998)
|-
| {{Version |o |0.9.2}}<ref name=openssl_0.9.x_notes />
| {{start date|1999|03|22|df=yes}}
|
| align="right" |
* Successor of 0.9.1c
| 0.9.2b (6 April 1999)
|-
| {{Version |o |0.9.3}}<ref name=openssl_0.9.x_notes />
| {{start date|1999|05|25|df=yes}}
|
| align="right" |
* Successor of 0.9.2b
| 0.9.3a (27 May 1999)
|-
| {{Version |o |0.9.4}}<ref name=openssl_0.9.x_notes />
| {{start date|1999|08|09|df=yes}}
|
| align="right" |
* Successor of 0.9.3a
| 0.9.4 (9 August 1999)
|-
| {{Version |o |0.9.5}}<ref name=openssl_0.9.x_notes />
| {{start date|2000|02|28|df=yes}}
|
| align="right" |
* Successor of 0.9.4
| 0.9.5a (1 April 2000)
|-
| {{Version |o |0.9.6}}<ref name=openssl_0.9.x_notes />
| {{start date|2000|09|24|df=yes}}
|
| align="right" |
* Successor of 0.9.5a
| 0.9.6m (17 March 2004)
|-
| {{Version |o |0.9.7}}<ref name=openssl_0.9.x_notes />
| {{start date|2002|12|31|df=yes}}
|
| align="right" |
* Successor of 0.9.6m
| 0.9.7m (23 February 2007)
|-
| {{Version |o |0.9.8}}<ref name=openssl_0.9.x_notes />
| {{start date|2005|07|05|df=yes}}
|
| align="right" |
* Successor of 0.9.7m
| 0.9.8zh (3 December 2015)
|-
| {{Version |o |1.0.0}}<ref name=openssl_1.0.0_notes>{{cite web |url=https://github.com/openssl/openssl/blob/master/NEWS.md#openssl-100 |title=OpenSSL 1.0.0 series notes |website=[[GitHub]] |access-date=2022-12-06}}</ref>
| {{start date|2010|03|29|df=yes}}
|
| align="right" |
* Successor of 0.9.8n
| 1.0.0t ({{end date|2015|12|03|df=yes}})
|-
| {{Version |o |1.0.1}}<ref name=openssl_1.0.1_notes>{{cite web |url=https://github.com/openssl/openssl/blob/master/NEWS.md#openssl-101 |title=OpenSSL 1.0.1 series notes |website=[[GitHub]] |access-date=2022-12-06}}</ref>
| {{start date|2012|03|14|df=yes}}
| {{end date|2016|12|31|df=yes}}
| align="right" |
* Successor of 1.0.0h
* Support for TLS/DTLS heartbeat{{Ref RFC|6520}}
* Support for [[Stream Control Transmission Protocol|SCTP]]
* Support for TLS keying material exporter{{Ref RFC|5705}}
* Support for DTLS key establishment for [[Secure Real-time Transport Protocol|SRTP]]{{Ref RFC|5764}}
* Next Protocol Negotiation
* PSS signatures in certificates, requests and [[certificate revocation list]]s (CRL)
* Support for password based recipient info for CMS
* Support for TLS 1.2 and TLS 1.1
* Preliminary [[FIPS 140]] capability for unvalidated 2.0 FIPS module
* [[Secure Remote Password protocol]] (SRP) support
| 1.0.1u ({{end date|2016|09|22|df=yes}})
|-
| {{Version |o |1.0.2}}<ref name=openssl_1.0.2_notes>{{cite web |url=https://github.com/openssl/openssl/blob/master/NEWS.md#openssl-102 |title=OpenSSL 1.0.2 series notes |website=[[GitHub]] |access-date=2022-12-06}}</ref>
| {{start date|2015|01|22|df=yes}}
| {{end date|2019|12|31|df=yes}}
| align="right" |
* Successor of 1.0.1l
* Suite B support for TLS 1.2 and DTLS 1.2
* Support for DTLS 1.2
* TLS automatic [[Elliptic-curve cryptography|elliptic curve]] (EC) selection
* API to set TLS supported signature algorithms and curves
* SSL_CONF configuration API
* TLS [[ECC Brainpool|Brainpool]] support
* [[Application-Layer Protocol Negotiation|ALPN]] support
* CMS support for [[RSA-PSS]], [[RSA-OAEP]], [[ECDH]] and [[Key derivation function|ANSI X9.42]]
* [[FIPS 140]] support
| 1.0.2u ({{end date|2019|12|20|df=yes}})
|-
| {{Version |o|1.1.0}}<ref name=openssl_1.1.0_notes>{{cite web |url=https://github.com/openssl/openssl/blob/master/NEWS.md#openssl-110 |title=OpenSSL 1.1.0 series notes |website=[[GitHub]] |access-date=2022-12-06}}</ref>
| {{start date|2016|8|25|df=yes}}
| {{end date|2019|09|11|df=yes}}
| align="right" |
* Successor of 1.0.2h
* Support for [[BLAKE2]]{{Ref RFC|7693}}
* Support for [[ChaCha20-Poly1305]]{{Ref RFC|8439}}
* Support for [[Curve25519|X25519]]{{Ref RFC|7748}}
* Support for [[DNS-based Authentication of Named Entities|DANE]] and [[Certificate Transparency]]
* Support for [[CCM mode|CCM]] Ciphersuites
* Support for extended master secret
* SSLv2 removed
* Kerberos ciphersuite support removed
* RC4 and 3DES removed from DEFAULT ciphersuites in libssl
* Remove DSS, SEED, IDEA, CAMELLIA, and AES-CCM from the DEFAULT cipherlist
* 40 and 56 bit cipher support removed from libssl
* [[FIPS 140]] support removed
| 1.1.0l ({{end date|2019|9|10|df=yes}})
|-
| {{Version |o|1.1.1 LTS}}<ref name=openssl_1.1.1_release_blog>{{Cite web |url=https://openssl-library.org/post/2018-09-11-release111/ |title=OpenSSL 1.1.1 Is Released |last=Caswell |first=Matt |date=2018-09-11 |access-date=2024-10-11 |website=OpenSSL Blog |publisher=OpenSSL Foundation}}</ref><ref name=openssl_1.1.1_notes>{{cite web |url=https://github.com/openssl/openssl/blob/master/NEWS.md#openssl-111 |title=OpenSSL 1.1.1 series notes |website=[[GitHub]] |access-date=2022-12-06}}</ref>
| {{start date|2018|9|11|df=yes}}
| {{end date|2023|9|11|df=yes}} ([[Long-term support|LTS]])
| align="right" |
* Successor of 1.1.0i
* Support for [[Transport Layer Security|TLS 1.3]]<ref>{{Cite web |url=https://openssl-library.org/post/2018-02-08-tlsv1.3/ |title=Using TLS1.3 With OpenSSL |last=Caswell |first=Matt |date=2018-02-08 |access-date=2024-10-11 |website=OpenSSL Blog |publisher=OpenSSL Foundation}}</ref><ref name=openssl_1.1.1_release_blog/>
* Support for [[SHA-3]]
* Support for [[Curve448|X448 and Ed448]]{{Ref RFC|7748}}
* Support for [[SipHash]]
* Support for [[ARIA (cipher)|ARIA]]
* Support for multi-prime [[RSA (cryptosystem)|RSA]]{{Ref RFC|8017}}
* Support for [[SM2 (algorithm)|SM2]], [[SM3 (hash function)|SM3]] and [[SM4 (cipher)|SM4]]
* [[Heartbeat (computing)|Heartbeat]] removed
* QNX support removed
| 1.1.1w (11 September 2023) 
|-
| {{Version |co|3.0 LTS}}<ref name=openssl_3.0.0_release_blog>{{Cite web |title=OpenSSL 3.0 Has Been Released! |url=https://openssl-library.org/post/2021-09-06-openssl3.final/ |access-date=2024-10-11 |website=OpenSSL Blog|date=September 7, 2021 }}</ref><ref name=openssl_3.0_notes>{{cite web |url=https://github.com/openssl/openssl/blob/master/NEWS.md#openssl-30 |title=OpenSSL 3.0 series notes |website=[[GitHub]] |access-date=2022-12-06}}</ref><br />{{Refn|group=note|name=a|The major version 2.0.0 was skipped due to its previous use in the OpenSSL FIPS module.<ref name=":0" />}}
| {{start date|2021|9|7|df=yes}}
| {{end date|2026|09|07|df=yes}} (LTS)
| align="right" |
* Relicensed to the [[Apache License 2.0]]<ref name=":0">{{Cite web |title=The Holy Hand Grenade of Antioch |url=https://openssl-library.org/post/2018-09-25-version/ |publisher=OpenSSL Blog |author=Matt Caswell |date=2018-11-28 |access-date=2024-10-11}}</ref>
* [[FIPS 140-2]] support re-added.
| Ongoing development
|-
|-
| {{Version |o|3.1}}<ref name=openssl_3.1.0_release_blog>{{Cite web |title=OpenSSL 3.1 Final Release |url=https://openssl-library.org/post/2023-03-07-openssl3.1release/ |access-date=2024-10-11 |website=OpenSSL Blog|date=March 7, 2023 }}</ref><ref name=openssl_3.1_notes>{{cite web |url=https://github.com/openssl/openssl/blob/master/NEWS.md#openssl-31 |title=OpenSSL 3.1 series notes |website=[[GitHub]] |access-date=2023-03-15}}</ref>
| {{start date|2023|3|14|df=yes}}
| {{end date|2025|3|14|df=yes}}
| align="right" |
* [[FIPS 140-3]] compliance
* Performance enhancements
| 3.1.8 (11 February 2025)
|-
| {{Version |co|3.2}}<ref name=openssl_3.2.0_release_blog>{{Cite web |title=OpenSSL 3.2.0 Final Release |url=https://openssl-library.org/post/2023-11-06-openssl32/ |access-date=2024-10-11 |website=OpenSSL Blog |date=November 23, 2023 |archive-date=December 7, 2024 |archive-url=https://web.archive.org/web/20241207234621/https://openssl-library.org/post/2023-11-06-openssl32/ |url-status=live }}</ref><ref name=openssl_3.2_notes>{{cite web |url=https://github.com/openssl/openssl/blob/master/NEWS.md#openssl-32 |title=OpenSSL 3.2 series notes |website=[[GitHub]] |access-date=2023-11-24}}</ref>
| {{start date|2023|11|23|df=yes}}
| {{end date|2025|11|23|df=yes}}
| align="right" |
* Client-side [[QUIC]] support
* TLS Certificate compression{{Ref RFC|8879}}
* Deterministic use of [[Elliptic Curve Digital Signature Algorithm|ECDSA]]{{Ref RFC|6979}}
* TLS raw public keys{{Ref RFC|7250}}
| Ongoing development
|-
| {{Version |co|3.3}}<ref name=openssl_3.3_final_release>{{Cite web |title=OpenSSL 3.3 Final Release |url=https://openssl-library.org/post/2024-04-10-3.3-final-release/ |access-date=2024-10-11 |website=OpenSSL Blog|date=April 10, 2024}}</ref>
| {{start date|2024|04|09|df=yes}}
| {{end date|2026|04|09|df=yes}}
|
|Ongoing development
|-
| {{Version |co|3.4}}<ref name=openssl_3.4_final_release>{{Cite web |title=OpenSSL 3.4 Final Release |url=https://openssl-corporation.org/post/2024-10-22-openssl-3-4-final/ |access-date=2024-11-22 |website=OpenSSL Blog |date=October 22, 2024 |archive-date=December 8, 2024 |archive-url=https://web.archive.org/web/20241208024058/https://openssl-corporation.org/post/2024-10-22-openssl-3-4-final/ |url-status=live}}</ref>
| {{start date|2024|10|22|df=yes}}
| {{end date|2026|10|22|df=yes}}
|
|Ongoing development
|-
| {{Version |c|3.5 LTS}}<ref name=openssl_3.5_final_release>{{Cite web |title=OpenSSL 3.5 Final Release |url=https://openssl-library.org/post/2025-04-08-openssl-35-final-release/ |access-date=2025-04-28 |website=OpenSSL Blog |date=April 8, 2025 |archive-date=April 25, 2025 |archive-url=https://web.archive.org/web/20250425182759/https://openssl-library.org/post/2025-04-08-openssl-35-final-release/ |url-status=live}}</ref>
| {{start date|2025|04|08|df=yes}}
| {{end date|2030|04|08|df=yes}} (LTS)
| align="right" |
* Support for PQC algorithms (ML-KEM, ML-DSA and SLH-DSA)
* Support for server side QUIC (RFC 9000)
* Support for 3rd party QUIC stacks including 0-RTT support
* Support added for opaque symmetric key objects (EVP_SKEY)
* A new configuration option no-tls-deprecated-ec to disable support for TLS groups deprecated in RFC8422
* A new configuration option enable-fips-jitter to make the FIPS provider to use the JITTER seed source
* Support for central key generation in CMP
* Support for multiple TLS keyshares and improved TLS key establishment group configurability
* API support for pipelining in provided cipher algorithms
|Ongoing development
|-
| colspan="5" | <small>{{Version |l |show=111100}}</small>
|}

== Algorithms ==

OpenSSL supports a number of different cryptographic algorithms:
; [[Cipher]]s:
: [[Advanced Encryption Standard|AES]], [[Blowfish (cipher)|Blowfish]], [[Camellia (cipher)|Camellia]], [[ChaCha20]], [[Poly1305]],  [[SEED]], [[CAST-128]], [[Data Encryption Standard|DES]], [[International Data Encryption Algorithm|IDEA]], [[RC2]], [[RC4]], [[RC5]], [[Triple DES]], [[GOST (block cipher)|GOST 28147-89]],<ref name="gost">{{cite web |url=http://cvs.openssl.org/fileview?f=openssl/engines/ccgost/README.gost |archive-url=https://archive.today/20130415122812/http://cvs.openssl.org/fileview?f=openssl/engines/ccgost/README.gost |url-status=dead |archive-date=2013-04-15 |title=GOST engine OpenSSL 1.0.0 README |publisher=cvs.openssl.org}}</ref> [[SM4 (cipher)|SM4]]
; [[Cryptographic hash function]]s:
: [[MD5]], [[MD4]], [[MD2 (cryptography)|MD2]], [[SHA-1]], [[SHA-2]], [[SHA-3]], [[RIPEMD-160]], [[MDC-2]], [[GOST (hash function)|GOST R 34.11-94]],<ref name="gost" /> [[BLAKE (hash function)#BLAKE2|BLAKE2]], [[Whirlpool (cryptography)|Whirlpool]],<ref>{{cite web|url=https://github.com/openssl/openssl/tree/master/crypto/whrlpool|title=OpenSSL source code, directory crypto/whrlpool|website=[[GitHub]]|access-date=2017-08-29|archive-date=February 17, 2019|archive-url=https://web.archive.org/web/20190217114449/https://github.com/openssl/openssl/tree/master/crypto/whrlpool|url-status=live}}</ref> [[SM3 (hash function)|SM3]]
; [[Public-key cryptography]]:
: [[RSA (algorithm)|RSA]], [[Digital Signature Algorithm|DSA]], [[Diffie–Hellman key exchange]],  [[Elliptic curve cryptography|Elliptic curve]], [[X25519]], [[Ed25519]], [[Curve448|X448]], [[Curve448|Ed448]], [[GOST R 34.10-2001]],<ref name="gost" /> [[SM2 (algorithm)|SM2]]

([[Perfect forward secrecy]] is supported using [[elliptic curve Diffie–Hellman]] since version 1.0.<ref>{{cite web|url=http://googleonlinesecurity.blogspot.com.au/2011/11/protecting-data-for-long-term-with.html|title=Protecting data for the long term with forward secrecy|access-date=2012-11-05|archive-date=March 4, 2016|archive-url=https://web.archive.org/web/20160304224153/https://googleonlinesecurity.blogspot.com.au/2011/11/protecting-data-for-long-term-with.html|url-status=live}}</ref>)

== FIPS 140 validation ==

[[FIPS 140]] is a U.S. Federal program for the testing and certification of cryptographic modules. An early FIPS 140-1 certificate for OpenSSL's FOM 1.0 was revoked in July 2006 "when questions were raised about the validated module's interaction with outside software." The module was re-certified in February 2007 before giving way to FIPS 140-2.<ref>{{cite web |url=http://www.gcn.com/online/vol1_no1/43142-1.html |title=NIST recertifies open source encryption module |publisher=gcn.com |url-status=dead |archive-url=https://web.archive.org/web/20071010000622/http://www.gcn.com/online/vol1_no1/43142-1.html |archive-date=2007-10-10}}</ref> OpenSSL 1.0.2 supported the use of the OpenSSL FIPS Object Module (FOM), which was built to deliver FIPS approved algorithms in a FIPS 140-2 validated environment.<ref>{{cite web |url=https://www.openssl.org/docs/fips.html |title=FIPS-140 |publisher=openssl.org |access-date=2019-11-12}}</ref><ref>{{cite web |date=2017-03-14 |url=https://www.openssl.org/docs/fips/UserGuide-2.0.pdf |title=OpenSSL User Guide for the OpenSSL FIPS Object Module v2.0 |publisher=openssl.org |access-date=2019-11-12 |archive-date=June 9, 2020 |archive-url=https://web.archive.org/web/20200609025558/https://www.openssl.org/docs/fips/UserGuide-2.0.pdf |url-status=live}}</ref> OpenSSL controversially decided to categorize the 1.0.2 architecture as 'end of life' or 'EOL', effective December 31, 2019, despite objections that it was the only version of OpenSSL that was currently available with support for FIPS mode.<ref name="openssl_blog_3.0_update">{{cite web |url=https://openssl-library.org/post/2019-11-07-3.0-update/ |title=Update on 3.0 Development, FIPS and 1.0.2 EOL |website=OpenSSL Blog |date=7 November 2019 |access-date=2024-10-11}}</ref> As a result of the EOL, many users were unable to properly deploy the FOM 2.0 and fell out of compliance because they did not secure extended support for the 1.0.2 architecture, although the FOM itself remained validated for eight months further.

The FIPS Object Module 2.0 remained FIPS 140-2 validated in several formats until September 1, 2020, when NIST deprecated the usage of FIPS 186-2 for [[Digital Signature Standard]] and designated all non-compliant modules as 'Historical'. This designation includes a caution to federal agencies that they should not include the module in any new procurements. All three of the OpenSSL validations were included in the deprecation – the OpenSSL FIPS Object Module (certificate #1747),<ref>{{cite web |url=https://csrc.nist.gov/projects/cryptographic-module-validation-program/certificate/1747 |title=Cryptographic Module Validation Program Certificate #1747 |website=Computer Security Resource Center |date=October 11, 2016}}</ref> OpenSSL FIPS Object Module SE (certificate #2398),<ref>{{cite web |url=https://csrc.nist.gov/projects/cryptographic-module-validation-program/certificate/2398 |title=Cryptographic Module Validation Program Certificate #2398 |website=Computer Security Resource Center |date=October 11, 2016 |access-date=October 29, 2020 |archive-date=October 26, 2020 |archive-url=https://web.archive.org/web/20201026130404/https://csrc.nist.gov/projects/cryptographic-module-validation-program/Certificate/2398 |url-status=live}}</ref> and OpenSSL FIPS Object Module RE (certificate #2473).<ref>{{cite web |url=https://csrc.nist.gov/projects/cryptographic-module-validation-program/certificate/2473 |title=Cryptographic Module Validation Program Certificate #2473 |website=Computer Security Resource Center |date=October 11, 2016}}</ref> Many 'private label' OpenSSL-based validations and clones created by consultants were also moved to the Historical List, although some FIPS validated modules with replacement compatibility avoided the deprecation, such as BoringCrypto from Google<ref>{{cite web |url=https://csrc.nist.gov/projects/cryptographic-module-validation-program/validated-modules/search?SearchMode=Advanced&Vendor=google&ModuleName=boringcrypto&Standard=140-2&CertificateStatus=Active&ValidationYear=0 |title=Cryptographic Module Validation Program search results |website=Computer Security Resource Center |date=October 11, 2016}}</ref> and CryptoComply from SafeLogic.<ref>{{cite web |url=https://csrc.nist.gov/projects/cryptographic-module-validation-program/validated-modules/search?SearchMode=Advanced&Vendor=safelogic&ModuleName=cryptocomply&Standard=140-2&CertificateStatus=Active&ValidationYear=0 |title=Cryptographic Module Validation Program search results |website=Computer Security Resource Center |date=October 11, 2016}}</ref>

The OpenSSL Management Committee announced a change in the versioning scheme.

Due to this change, the major number of the next major version would have been doubled, since the OpenSSL FIPS module already occupied this number. Therefore, the decision was made to skip the OpenSSL 2.0 version number and continue with OpenSSL 3.0 .

OpenSSL 3.0 restored FIPS mode and underwent FIPS 140-2 testing, but with significant delays: The effort was first kicked off in 2016 with support from SafeLogic<ref>{{cite news |url=https://gcn.com/articles/2016/07/20/openssl-fips |title=Getting government approval of a more secure OpenSSL |last=Schneider |first=Troy K. |date=20 July 2016 |work=GCN: Technology, Tools, and Tactics for Public Sector IT |archive-date=May 9, 2021 |access-date=October 29, 2020 |archive-url=https://web.archive.org/web/20210509143554/https://gcn.com/articles/2016/07/20/openssl-fips |url-status=live}}</ref><ref>{{cite news |url=https://www.fedscoop.com/openssl-us-government-safelogic-fips-140-2-2016/ |first=Shaun |last=Waterman |title=SafeLogic saves the day for feds' use of OpenSSL |date=21 July 2016 |work=FedScoop}}</ref><ref>{{cite news |url=https://www.infoworld.com/article/3098868/reworked-openssl-on-track-for-government-validation.html |first=Fahmida Y. |last=Rashid |title=Reworked OpenSSL on track for government validation |date=26 July 2016 |work=InfoWorld}}</ref> and further support from Oracle in 2017,<ref>{{cite news |url=https://www.dbta.com/Editorial/News-Flashes/Oracle-SafeLogic-and-OpenSSL-Join-Forces-to-Update-FIPS-Module-119707.aspx |first=Joyce |last=Wells |title=Oracle, SafeLogic and OpenSSL Join Forces to Update FIPS Module |date=3 August 2017 |work=Database Trends and Applications}}</ref><ref>{{cite news |url=https://www.eweek.com/security/oracle-joins-safelogic-to-develop-fips-module-for-openssl-security |first=Sean Michael |last=Kerner |title=Oracle Joins SafeLogic to Develop FIPS Module for OpenSSL Security |date=4 August 2017 |work=eWeek}}</ref> but the process has been challenging.<ref>{{cite web |url=https://openssl-library.org/post/2020-10-20-openssl3.0alpha7/ |title=OpenSSL 3.0 Alpha7 Release |date=20 October 2020 |access-date=2024-10-11 |website=OpenSSL Blog |archive-date=October 14, 2024 |archive-url=https://web.archive.org/web/20241014051322/https://openssl-library.org/post/2020-10-20-openssl3.0alpha7/ |url-status=live}}</ref>

On October 20, 2020, the OpenSSL FIPS Provider 3.0 was added to the CMVP Implementation Under Test List, which reflected an official engagement with a testing lab to proceed with a FIPS 140-2 validation. This resulted in a slew of certifications in the following months.<ref>{{cite web |url=https://csrc.nist.gov/projects/cryptographic-module-validation-program/validated-modules/search?SearchMode=Basic&ModuleName=OpenSSL&CertificateStatus=Active&ValidationYear=0 |title=Cryptographic Module Validation Program: OpenSSL |website=Computer Security Resource Center |date=October 11, 2016 |access-date=September 24, 2021 |archive-date=April 14, 2021 |archive-url=https://web.archive.org/web/20210414133436/https://csrc.nist.gov/projects/cryptographic-module-validation-program/validated-modules/search?SearchMode=Basic&ModuleName=openssl&CertificateStatus=Active&ValidationYear=0 |url-status=live}}</ref>

== Licensing ==

OpenSSL was dual-licensed under the OpenSSL License and the SSLeay License, which means that the terms of either licenses can be used.<ref>{{cite web |url=https://www.openssl.org/source/license.html |title=OpenSSL: Source, License |publisher=openssl.org |access-date=February 5, 2015 |archive-date=January 18, 2019 |archive-url=https://web.archive.org/web/20190118094240/https://www.openssl.org/source/license.html |url-status=live}}</ref> The OpenSSL License is [[Apache License]] 1.0 and SSLeay License bears some similarity to a 4-clause [[BSD License]].
As the OpenSSL License was [[Apache License]] 1.0, but not Apache License 2.0, it requires the phrase "this product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit" to appear in advertising material and any redistributions (Sections 3 and 6 of the OpenSSL License). Due to this restriction, the OpenSSL License and the Apache License 1.0 are incompatible with the [[GNU General Public License|GNU GPL]].<ref>{{cite web |url=http://www.fsf.org/licensing/licenses |title=Licenses – Free Software Foundation |publisher=fsf.org |access-date=January 4, 2008 |archive-date=January 24, 2008 |archive-url=https://web.archive.org/web/20080124043540/http://www.fsf.org/licensing/licenses |url-status=live}}</ref>
Some GPL developers have added an ''OpenSSL exception'' to their licenses that specifically permits using OpenSSL with their system. GNU [[Wget]] and [[climm]] both use such exceptions.<ref>{{cite web |url=http://users.ugent.be/~bpuype/wget |title=WGET 1.10.2 for Windows (win32) |publisher=users.ugent.be |url-status=dead |archive-url=https://web.archive.org/web/20080102164139/http://users.ugent.be/~bpuype/wget/ |archive-date=2008-01-02}}</ref><ref>{{cite web |url=http://www.climm.org/download.shtml.en |title=Releases of source and binaries |publisher=climm.org |access-date=30 November 2010 |url-status=dead |archive-url=https://web.archive.org/web/20110212024627/http://www.climm.org/download.shtml.en |archive-date=12 February 2011}}</ref> Some packages (like [[Deluge (software)|Deluge]]) explicitly modify the GPL license by adding an extra section at the beginning of the license documenting the exception.<ref>{{cite web |url=http://git.deluge-torrent.org/deluge/plain/LICENSE |title=Deluge LICENSE file |publisher=deluge-torrent.org |access-date=24 January 2013 |archive-date=December 3, 2013 |archive-url=https://web.archive.org/web/20131203035654/http://git.deluge-torrent.org/deluge/plain/LICENSE |url-status=live}}</ref> Other packages use the [[GNU Lesser General Public License|LGPL]]-licensed [[GnuTLS]], [[BSD licenses|BSD]]-licensed [[Botan (programming library)|Botan]], or [[Mozilla Public License|MPL]]-licensed [[Network Security Services|NSS]], which perform the same task.

OpenSSL announced in August 2015 that it would require most contributors to sign a [[Contributor License Agreement]] (CLA), and that OpenSSL would eventually be [[Software relicensing|relicensed]] under the terms of [[Apache License&nbsp;2.0]].<ref>{{cite web
 | url = https://openssl-library.org/post/2015-08-01-cla/
 | title = License Agreements and Changes Are Coming
 | date = 1 August 2015 | access-date = 2024-10-11
 | last = Salz | first = Rich | website = openssl.org
}}</ref> This process commenced in March 2017,<ref>{{Cite web |url=https://www.coreinfrastructure.org/news/announcements/2017/03/openssl-re-licensing-apache-license-v-20-encourage-broader-use-other-foss |title=OpenSSL Re-licensing to Apache License v. 2.0 To Encourage Broader Use with Other FOSS Projects and Products |date=2017-03-23 |access-date=2018-08-06 |archive-url=https://web.archive.org/web/20170718040958/https://www.coreinfrastructure.org/news/announcements/2017/03/openssl-re-licensing-apache-license-v-20-encourage-broader-use-other-foss |archive-date=2017-07-18}}</ref> and was complete in 2018.<ref name = "Various, Red Hat, 2019" >{{ Cite web | url = https://opensource.com/article/19/2/top-foss-legal-developments | title = Top 10 FOSS legal developments of 2018 | access-date = 2019-09-28 | first1 = Victoria | last1 = Lee | first2 = Mark | last2 = Radcliffe | first3 = Chris | last3 = Stevenson | date = 2019-02-05 | website = Opensource.com, [[Red Hat]] | quote = The OpenSSL project announced that it had completed its shift from the OpenSSL/SSLeay license to the Apache Software License version 2 (ASLv2). | archive-url = https://web.archive.org/web/20190205110130/https://opensource.com/article/19/2/top-foss-legal-developments | archive-date = 2019-02-05  | df = dmy-all}}</ref>

On 7 September 2021, OpenSSL 3.0.0 was released under the Apache License 2.0.<ref>{{Cite web |url=https://wiki.openssl.org/index.php/OpenSSL_3.0#License_Change |title=OpenSSL 3.0 License Change |date=2021-09-22 |access-date=2021-09-24 |archive-date=January 17, 2025 |archive-url=https://web.archive.org/web/20250117002813/https://wiki.openssl.org/index.php/OpenSSL_3.0#License_Change |url-status=live}}</ref>

== Notable vulnerabilities ==

=== Denial of service (DOS): ASN.1 parsing ===

OpenSSL 0.9.6k has a bug where certain [[ASN.1]] sequences triggered a large number of recursions on Windows machines, discovered on November 4, 2003. Windows could not handle large recursions correctly, so OpenSSL would crash as a result. Being able to send arbitrary large numbers of ASN.1 sequences would cause OpenSSL to crash as a result.

=== OCSP stapling vulnerability ===

When creating a handshake, the client could send an incorrectly formatted ClientHello message, leading to OpenSSL parsing more than the end of the message. Assigned the identifier {{CVE|2011-0014}} by the CVE project, this affected all OpenSSL versions 0.9.8h to 0.9.8q and OpenSSL 1.0.0 to 1.0.0c. Since the parsing could lead to a read on an incorrect memory address, it was possible for the attacker to cause a [[Denial-of-service attack|DoS]]. It was also possible that some applications expose the contents of parsed [[OCSP]] extensions, leading to an attacker being able to read the contents of memory that came after the ClientHello.<ref>{{cite web|title=OpenSSL Updates Fix Critical Security Vulnerabilities|date=9 August 2014|url=https://blogs.comodo.com/it-security/openssl-updates-fix-critical-security-vulnerabilities/|access-date=25 August 2014|df=mdy-all|archive-date=August 26, 2014|archive-url=https://web.archive.org/web/20140826120554/https://blogs.comodo.com/it-security/openssl-updates-fix-critical-security-vulnerabilities/|url-status=dead}}</ref>

=== ASN.1 BIO vulnerability ===

When using Basic Input/Output (BIO)<ref>{{cite web |url=https://tools.cisco.com/security/center/viewAlert.x?alertId=25706 |title=OpenSSL ASN.1 asn1_d2i_read_bio() Heap Overflow Vulnerability |publisher=Cisco |access-date=May 9, 2016 |archive-date=June 10, 2016 |archive-url=https://web.archive.org/web/20160610123316/https://tools.cisco.com/security/center/viewAlert.x?alertId=25706 |url-status=live}}</ref> or FILE based functions to read untrusted [[Distinguished Encoding Rules|DER]] format data, OpenSSL is vulnerable. This vulnerability was discovered on April 19, 2012, and was assigned the CVE identifier {{CVE|2012-2110}}. While not directly affecting the SSL/TLS code of OpenSSL, any application that was using ASN.1 functions (particularly d2i_X509 and d2i_PKCS12) were also not affected.<ref>{{cite web |url=https://www.openssl.org/news/secadv_20120419.txt |title=ASN1 BIO vulnerability |publisher=OpenSSL |access-date=February 5, 2015 |archive-date=March 2, 2015 |archive-url=https://web.archive.org/web/20150302121643/http://www.openssl.org/news/secadv_20120419.txt |url-status=live}}</ref>

=== SSL, TLS and DTLS plaintext recovery attack ===

In handling CBC cipher-suites in SSL, TLS, and DTLS, OpenSSL was found vulnerable to a timing attack during the MAC processing. Nadhem Alfardan and Kenny Paterson discovered the problem, and published their findings<ref>{{cite web|url=http://www.isg.rhul.ac.uk/tls/|title=On the Security of RC4 in TLS|publisher=Royal Holloway Department of Information Security|access-date=April 29, 2014|archive-date=March 15, 2013|archive-url=https://web.archive.org/web/20130315084623/http://www.isg.rhul.ac.uk/tls/|url-status=dead}}</ref> on February 5, 2013. The vulnerability was assigned the CVE identifier {{CVE|2013-0169}}.

=== Predictable private keys (Debian-specific) ===

OpenSSL's pseudo-[[random number generator]] acquires entropy using complex programming methods. To keep the [[Valgrind]] analysis tool from issuing associated warnings, a maintainer of the [[Debian]] distribution applied a [[patch (computing)|patch]] to Debian's variant of the OpenSSL suite, which inadvertently broke its random number generator by limiting the overall number of private keys it could generate to 32,768.<ref>{{Cite web |title=research!rsc: Lessons from the Debian/OpenSSL Fiasco |url=http://research.swtch.com/openssl |website=research.swtch.com |access-date=2015-08-12|df=mdy-all}}</ref><ref>{{Cite web |title=SSLkeys |website=Debian Wiki |url=https://wiki.debian.org/SSLkeys  |access-date=2015-06-19|df=mdy-all}}</ref> The broken version was included in the Debian release of September 17, 2006 (version 0.9.8c-1), also compromising other Debian-based distributions, for example [[Ubuntu (operating system)|Ubuntu]]. Ready-to-use [[exploit (computer security)|exploits]] are easily available.<ref>{{Cite web |title=Debian OpenSSL – Predictable PRNG Bruteforce SSH Exploit Python |website=Exploits Database |url=https://www.exploit-db.com/exploits/5720/ |access-date=2015-08-12 |date=2008-06-01 |df=mdy-all |archive-date=February 6, 2025 |archive-url=https://web.archive.org/web/20250206223039/https://www.exploit-db.com/exploits/5720 |url-status=live}}</ref>

The error was reported by Debian on May 13, 2008. On the Debian&nbsp;4.0 distribution (etch), these problems were fixed in version 0.9.8c-4etch3, while fixes for the Debian&nbsp;5.0 distribution (lenny) were provided in version 0.9.8g-9.<ref name="dsa-1571-1">{{cite web |title=DSA-1571-1 openssl – predictable random number generator |url=http://www.debian.org/security/2008/dsa-1571 |publisher=[[Debian]] Project |date=May 13, 2008 |access-date=August 5, 2012 |archive-date=March 9, 2011 |archive-url=https://web.archive.org/web/20110309045023/http://www.debian.org/security/2008/dsa-1571 |url-status=live}}</ref>

=== {{anchor|Heartbleed bug}}Heartbleed ===

{{Main|Heartbleed}}

[[File:Heartbleed.svg|thumb|A logo representing the Heartbleed bug]]

OpenSSL versions 1.0.1 through 1.0.1f have a severe memory handling [[software bug|bug]] in their implementation of the [[Transport Layer Security|TLS]] Heartbeat Extension that could be used to reveal up to 64&nbsp;[[Kibibyte|KB]] of the application's memory with every [[heartbeat (computing)|heartbeat]]<ref>{{cite web|title=OpenSSL Security Advisory [07 Apr 2014]|url=https://www.openssl.org/news/secadv_20140407.txt|author=OpenSSL.org|access-date=9 April 2014|date=7 April 2014|df=mdy-all|archive-date=April 8, 2014|archive-url=https://web.archive.org/web/20140408195036/https://www.openssl.org/news/secadv_20140407.txt|url-status=dead}}</ref><ref>{{Cite web| last = OpenSSL| title = TLS heartbeat read overrun (CVE-2014-0160)| access-date = 2014-04-08| date = 2014-04-07| url = https://www.openssl.org/news/secadv_20140407.txt| df = mdy-all| archive-date = April 8, 2014| archive-url = https://web.archive.org/web/20140408195036/https://www.openssl.org/news/secadv_20140407.txt| url-status = dead}}</ref> ({{CVE|2014-0160}}). By reading the memory of the web server, attackers could access sensitive data, including the server's [[public-key cryptography|private key]].<ref name="hb">{{Cite web| last = Codenomicon Ltd| title = Heartbleed Bug| access-date = 2014-04-08| date = 2014-04-08| url = http://heartbleed.com/| df = mdy-all| archive-date = April 7, 2014| archive-url = https://web.archive.org/web/20140407203519/http://heartbleed.com/| url-status = live}}</ref> This could allow attackers to decode earlier [[eavesdropping|eavesdropped]] communications if the encryption protocol used does not ensure [[perfect forward secrecy]]. Knowledge of the private key could also allow an attacker to mount a [[man-in-the-middle attack]] against any future communications.{{citation needed|date=April 2019}} The vulnerability might also reveal unencrypted parts of other users' sensitive requests and responses, including [[session cookie]]s and passwords, which might allow attackers to [[Session hijacking|hijack the identity]] of another user of the service.<ref name="ipsec">{{cite web |url=http://ipsec.pl/ssl-tls/2014/why-heartbleed-dangerous-exploiting-cve-2014-0160.html |title=Why Heartbleed is dangerous? Exploiting CVE-2014-0160 |year=2014 |publisher=IPSec.pl |access-date=April 8, 2014 |archive-date=April 8, 2014 |archive-url=https://web.archive.org/web/20140408224556/http://ipsec.pl/ssl-tls/2014/why-heartbleed-dangerous-exploiting-cve-2014-0160.html |url-status=dead}}</ref>

At its disclosure on April 7, 2014, around 17% or half a million of the Internet's secure [[web servers]] certified by [[Certificate authority|trusted authorities]] were believed to have been vulnerable to the attack.<ref>{{cite web|last=Mutton|first=Paul|title=Half a million widely trusted websites vulnerable to Heartbleed bug|url=http://news.netcraft.com/archives/2014/04/08/half-a-million-widely-trusted-websites-vulnerable-to-heartbleed-bug.html|publisher=Netcraft Ltd.|access-date=8 April 2014|date=8 April 2014|df=mdy-all|archive-date=November 19, 2014|archive-url=https://web.archive.org/web/20141119102520/http://news.netcraft.com/archives/2014/04/08/half-a-million-widely-trusted-websites-vulnerable-to-heartbleed-bug.html|url-status=live}}</ref> However, Heartbleed can affect both the server and client.

=== {{anchor|CVE-2014-0224}}CCS injection vulnerability ===

The CCS Injection Vulnerability ({{CVE|2014-0224}}) is a security bypass vulnerability that results from a weakness in OpenSSL methods used for keying material.<ref>{{cite web |url=http://www.cyberoam.com/blog/openssl-continues-to-bleed-out-more-flaws-more-critical-vulnerabilities-found/ |title=OpenSSL continues to bleed out more flaws – more critical vulnerabilities found |year=2014 |publisher=Cyberoam Threat Research Labs |access-date=2014-06-13 |archive-url=https://web.archive.org/web/20140619034859/http://www.cyberoam.com/blog/openssl-continues-to-bleed-out-more-flaws-more-critical-vulnerabilities-found/ |archive-date=2014-06-19 |url-status=dead |df=mdy-all}}</ref>

This vulnerability can be exploited through the use of a man-in-the-middle attack,<ref>{{cite web |url=https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-0224 |title=CVE-2014-0224 |year=2014 |publisher=CVE |access-date=June 13, 2014 |archive-date=August 1, 2014 |archive-url=https://web.archive.org/web/20140801203134/https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-0224 |url-status=live}}</ref> where an attacker may be able to decrypt and modify traffic in transit. A remote unauthenticated attacker could exploit this vulnerability by using a specially crafted handshake to force the use of weak keying material. Successful exploitation could lead to a security bypass condition where an attacker could gain access to potentially sensitive information. The attack can only be performed between a vulnerable client ''and'' server.

OpenSSL clients are vulnerable in all versions of OpenSSL before the versions 0.9.8za, 1.0.0m and 1.0.1h. Servers are only known to be vulnerable in OpenSSL 1.0.1 and 1.0.2-beta1. Users of OpenSSL servers earlier than 1.0.1 are advised to upgrade as a precaution.<ref>{{cite web |url=https://www.openssl.org/news/secadv_20140605.txt |title=OpenSSL Security Advisory |date=5 June 2014 |publisher=OpenSSL |df=mdy-all |access-date=June 13, 2014 |archive-date=April 30, 2024 |archive-url=https://web.archive.org/web/20240430142011/https://www.openssl.org/news/secadv_20140605.txt |url-status=dead}}</ref>

=== {{anchor|CVE-2015-0291}}ClientHello sigalgs DoS ===

This vulnerability ({{CVE|2015-0291}}) allows anyone to take a certificate, read its contents and modify it accurately to abuse the vulnerability causing a certificate to crash a client or server. If a client connects to an OpenSSL 1.0.2 server and renegotiates with an invalid signature algorithms extension, a null-pointer dereference occurs. This can cause a DoS attack against the server.

A Stanford Security researcher, David Ramos, had a private exploit and presented it to the OpenSSL team, which then patched the issue.

OpenSSL classified the bug as a high-severity issue, noting version 1.0.2 was found vulnerable.<ref>{{cite web |url=http://freedomhacker.net/openssl-patches-severe-denial-of-service-vulnerability-3818/ |title=OpenSSL Patches Severe Denial-of-Service Vulnerability |date=20 March 2015 |publisher=Brandon Stosh |df=mdy-all |access-date=March 20, 2015 |archive-date=April 2, 2015 |archive-url=https://web.archive.org/web/20150402102240/http://freedomhacker.net/openssl-patches-severe-denial-of-service-vulnerability-3818/ |url-status=live}}</ref>

=== {{anchor|CVE-2016-0701}}Key recovery attack on Diffie–Hellman small subgroups ===

This vulnerability ({{CVE|2016-0701}}) allows, when some particular circumstances are met, to recover the OpenSSL server's private Diffie–Hellman key. An Adobe System Security researcher, Antonio Sanso, privately reported the vulnerability.

OpenSSL classified the bug as a high-severity issue, noting only version 1.0.2 was found vulnerable.<ref>{{cite web |url=https://arstechnica.com/security/2016/01/high-severity-bug-in-openssl-allows-attackers-to-decrypt-https-traffic/ |title=High-severity bug in OpenSSL allows attackers to decrypt HTTPS traffic |date=28 January 2016 |work=Ars Technica |first=Dan |last=Goodlin |df=mdy-all |access-date=June 14, 2017 |archive-date=November 20, 2016 |archive-url=https://web.archive.org/web/20161120091808/http://arstechnica.com/security/2016/01/high-severity-bug-in-openssl-allows-attackers-to-decrypt-https-traffic/ |url-status=live}}</ref>

== Forks ==

=== {{Anchor|assl}}Agglomerated SSL ===

In 2009, after frustrations with the original OpenSSL API, Marco Peereboom, an OpenBSD developer at the time, forked the original API by creating Agglomerated SSL (assl),<ref>{{cite web |url= https://github.com/conformal/assl |title= Agglomerated SSL |website= [[GitHub]] |date= 2010-09-07 |access-date= 2024-12-09 |archive-date= December 9, 2024 |archive-url= https://web.archive.org/web/20241209174330/https://github.com/conformal/assl |url-status= live}}</ref> which reuses OpenSSL API under the hood, but provides a much simpler external interface.<ref>{{cite web |url= http://ports.su/security/assl |title= security/assl: assl-1.5.0p0v0 – hide awful SSL API in a sane interface |work= [[OpenBSD ports]] |date= 2014-05-22 |access-date= 2015-02-10 |archive-date= February 10, 2015 |archive-url= https://web.archive.org/web/20150210224924/http://ports.su/security/assl |url-status= live}}</ref>  It has since been deprecated in light of the [[LibreSSL]] fork circa 2015.

=== LibreSSL ===

{{Main|LibreSSL}}

In April 2014 in the wake of [[Heartbleed]], members of the [[OpenBSD]] project [[fork (software development)|fork]]ed OpenSSL starting with the 1.0.1g branch, to create a project named [[LibreSSL]].<ref name="fork">{{cite web |url=http://www.undeadly.org/cgi?action=article&sid=20140415093252&mode=expanded |title=OpenBSD has started a massive strip-down and cleanup of OpenSSL |date=2014-04-15 |work=OpenBSD journal |access-date=April 21, 2014 |archive-date=July 1, 2014 |archive-url=https://web.archive.org/web/20140701104920/http://undeadly.org/cgi?action=article&sid=20140415093252&mode=expanded |url-status=live}}</ref> In the first week of pruning the OpenSSL's [[codebase]], more than 90,000 lines of C code had been removed from the fork.<ref>{{cite web|title=OpenBSD forks, prunes, fixes OpenSSL|url=https://www.zdnet.com/article/openbsd-forks-prunes-fixes-openssl/|publisher=ZDNet|access-date=21 April 2014|date=21 April 2014|archive-date=April 21, 2014|archive-url=https://web.archive.org/web/20140421235922/http://www.zdnet.com/openbsd-forks-prunes-fixes-openssl-7000028613/|url-status=live}}</ref>

=== {{Anchor|BORINGSSL}}BoringSSL ===

In June 2014, [[Google]] announced its own fork of OpenSSL dubbed BoringSSL.<ref>{{cite web|url=https://boringssl.googlesource.com/boringssl/|title=BoringSSL|website=Git at Google|access-date=December 28, 2015|archive-date=February 17, 2018|archive-url=https://web.archive.org/web/20180217042214/https://boringssl.googlesource.com/boringssl/|url-status=live}}</ref> Google plans to co-operate with OpenSSL and LibreSSL developers.<ref>{{cite web |title=Google unveils independent 'fork' of OpenSSL called 'BoringSSL' |date=2014-06-21 |work=Ars Technica |url=https://arstechnica.com/security/2014/06/google-unveils-independent-fork-of-openssl-called-boringssl/ |access-date=June 14, 2017 |archive-date=June 23, 2014 |archive-url=https://web.archive.org/web/20140623192851/http://arstechnica.com/security/2014/06/google-unveils-independent-fork-of-openssl-called-boringssl/ |url-status=live}}</ref><ref>{{cite web|title=BoringSSL|date=2014-06-20|work=Adam Langley's Weblog|url=https://www.imperialviolet.org/2014/06/20/boringssl.html|access-date=September 22, 2015|archive-date=June 1, 2018|archive-url=https://web.archive.org/web/20180601042454/https://www.imperialviolet.org/2014/06/20/boringssl.html|url-status=live}}</ref><ref>{{cite web|url=https://nakedsecurity.sophos.com/2014/06/24/boringssl-wants-kill-the-excitement-that-led-to-heartbleed/|title=BoringSSL wants to kill the excitement that led to Heartbleed|date=24 June 2014|publisher=Sophos|access-date=October 24, 2016|archive-date=February 14, 2018|archive-url=https://web.archive.org/web/20180214073437/https://nakedsecurity.sophos.com/2014/06/24/boringssl-wants-kill-the-excitement-that-led-to-heartbleed/|url-status=dead}}</ref> Google has since developed a new library, Tink, based on BoringSSL.<ref>{{Cite web|url=https://medium.com/asecuritysite-when-bob-met-alice/goodbye-openssl-and-hello-to-google-tink-583163cfd76c|title=Goodbye OpenSSL, and Hello To Google Tink|first=Bill|last=Buchanan|date=2018-08-30|website=Medium|access-date=2019-04-04}}</ref>

=== {{Anchor|AWS-LC}}AWS-LC ===

In September 2020, it was released as a general-purpose cryptographic library maintained by the [[Amazon Web Services]] Cryptography team to be used in the AWS cloud computing platform. It іs based on code from the OpenSSL and BoringSSL projects.<ref>{{cite web |url= https://github.com/aws/aws-lc |title= AWS-LC is a general-purpose cryptographic library |website= [[GitHub]] |date= 2020-09-04 |access-date= 2024-12-08}}</ref>

=== {{Anchor|QuicTLS}}QuicTLS ===

QuicTLS is a collaborative fork between [[Akamai]] and [[Microsoft]], based on OpenSSL 3.3 release. Some features and fixes are cherry-picked from the current OpenSSL repo.<ref>{{cite web |url= https://github.com/quictls/quictls |title=  The official repository for the QuicTLS project |website= [[GitHub]] |date= 2025-05-07 |access-date= 2025-05-07}}</ref>

== Criticisms ==

=== Backwards compatibility ===

Among developers communities, OpenSSL is often cited for introducing API compatibility breakage with each new major version,<ref>{{Cite web|url=https://github.com/brave/brave-browser/issues/22305|title=OpenSSL 3 breaks webpack build · Issue #22305 · brave/brave-browser|website=GitHub|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208042515/https://github.com/brave/brave-browser/issues/22305|url-status=live}}</ref><ref>{{Cite web|url=https://bbs.archlinux.org/viewtopic.php?id=277577|title=openssl version 3.0 in arch? / Newbie Corner / Arch Linux Forums|website=bbs.archlinux.org|access-date=February 25, 2023|archive-date=May 16, 2024|archive-url=https://web.archive.org/web/20240516183345/https://bbs.archlinux.org/viewtopic.php?id=277577|url-status=live}}</ref><ref>{{Cite web|url=https://discourse.ubuntu.com/t/openssl-3-0-transition-plans/24453|title=OpenSSL 3.0 transition plans|date=April 6, 2022|website=Ubuntu Community Hub|access-date=February 25, 2023|archive-date=December 25, 2024|archive-url=https://web.archive.org/web/20241225033457/https://discourse.ubuntu.com/t/openssl-3-0-transition-plans/24453|url-status=live}}</ref><ref>{{Cite web|url=https://github.com/nginx/unit/issues/597|title=OpenSSL 3.0 Compatibility · Issue #597 · nginx/unit|website=GitHub|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208043018/https://github.com/nginx/unit/issues/597|url-status=live}}</ref> which requires software adaptations that tend to delay new version adoptions.<ref>{{Cite web|url=https://discuss.python.org/t/our-future-with-openssl/21486|title=Our future with OpenSSL|date=November 28, 2022|website=Discussions on Python.org|access-date=February 25, 2023|archive-date=February 25, 2023|archive-url=https://web.archive.org/web/20230225163414/https://discuss.python.org/t/our-future-with-openssl/21486|url-status=live}}</ref> This, combined with the fact that previous releases are generally maintained for no more than two years after a new major one is released<ref name="openssl_3.0.0_release_blog" /> tends to force some vendors to anticipate software migrations very early while still having little time left<ref>{{Cite web|url=https://www.redhat.com/en/blog/experience-bringing-openssl-30-rhel-and-fedora|title=The experience of bringing OpenSSL 3.0 into Red Hat Enterprise Linux and Fedora|website=www.redhat.com}}</ref> to update to a new release, sometimes at the risk of losing some compatibility with existing software<ref>{{Cite web|url=https://groups.google.com/g/help-cfengine/c/45i4ROevUVw|title=Compile against OpenSSL 3.X|website=groups.google.com|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208153714/https://groups.google.com/g/help-cfengine/c/45i4ROevUVw|url-status=live}}</ref><ref>{{Cite web|url=https://forum.eset.com/topic/32613-eset-management-agent-rhel-9x-openssl-30x/|title=ESET Management Agent (RHEL 9.x, OpenSSL 3.0.x)|website=ESET Security Forum|date=June 6, 2022|access-date=February 25, 2023|archive-date=December 9, 2024|archive-url=https://web.archive.org/web/20241209230105/https://forum.eset.com/topic/32613-eset-management-agent-rhel-9x-openssl-30x/|url-status=live}}</ref> or risking regressions.<ref>{{Cite web|url=https://bugs.python.org/issue46313|title=Issue 46313: SSLObject does not raise SSLEOFError on OpenSSL 3 - Python tracker|website=bugs.python.org|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208033439/https://bugs.python.org/issue46313|url-status=live}}</ref><ref>{{Cite web|url=https://www.tenable.com/plugins/nessus/164507|title=RHEL 9 : openssl (RHSA-2022:6224)|website=www.tenable.com|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208042937/https://www.tenable.com/plugins/nessus/164507|url-status=live}}</ref>

=== Delay between releases ===

While [[long-term support]] (LTS) releases are maintained for 5 years,<ref name='releasestrat'/> accumulated delays in release time frames tend to force operating system vendors to stay on the last supported release longer, leaving less margin when the new version is available. For example, OpenSSL 3.0 was initially expected for Q4 2019<ref name="openssl_blog_3.0_update" /> and was finally issued 21 months later<ref name="openssl_3.0.0_release_blog" /> without extending the expected end of support for previously supported version 1.1.1, and this despite the significant changes that required adaptations to existing software.

=== Significant performance regressions ===

The reduced support delay of version 1.1.1 mentioned above causes further concerns to users whose workloads are sensitive to performance. Some time after general availability of 3.0, some users started to report serious performance regressions affecting this version in multi-threaded environments, many citing the inefficient use of locks in frequent low-level operations, citing slowdowns from 80 to 400 times.<ref>{{Cite web|url=https://github.com/openssl/openssl/issues/17064|title=Massive performance degradation in OpenSsl 3.0 if used in a heavy multi threaded server application · Issue #17064 · openssl/openssl|website=GitHub|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208114743/https://github.com/openssl/openssl/issues/17064|url-status=live}}</ref><ref>{{Cite web|url=https://github.com/openssl/openssl/issues/17950|title=Performance issue with Openssl 3.0 in multi threaded application when using d2i_x509 · Issue #17950 · openssl/openssl|website=GitHub|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208051208/https://github.com/openssl/openssl/issues/17950|url-status=live}}</ref><ref>{{Cite web|url=https://github.com/openssl/openssl/issues/18814|title=Severe efficiency degradation of credential loading in comparison to 1.1.1 · Issue #18814 · openssl/openssl|website=GitHub|access-date=February 25, 2023|archive-date=December 7, 2024|archive-url=https://web.archive.org/web/20241207231338/https://github.com/openssl/openssl/issues/18814|url-status=live}}</ref><ref>{{Cite web|url=https://github.com/openssl/openssl/issues/20286|title=3.0 performance degraded due to locking · Issue #20286 · openssl/openssl|website=GitHub}}</ref><ref>{{Cite web|url=https://github.com/nodejs/node/issues/43128|title=High cpu usage for outbound ssl requests after upgrading from v16.15.0 to v18.1.0 · Issue #43128 · nodejs/node|website=GitHub|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208011158/https://github.com/nodejs/node/issues/43128|url-status=live}}</ref><ref>{{Cite web|url=https://github.com/openssl/openssl/issues/18472|title=Massive performance degradation in OpenSsl 3.0 FIPS provider · Issue #18472 · openssl/openssl|website=GitHub|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208192721/https://github.com/openssl/openssl/issues/18472|url-status=live}}</ref><ref>{{Cite web|url=https://github.com/openssl/openssl/issues/16791|title=Performance measurements · Issue #16791 · openssl/openssl|website=GitHub|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208124557/https://github.com/openssl/openssl/issues/16791|url-status=live}}</ref><ref>{{Cite web|url=https://github.com/openssl/openssl/issues/15199|title=PEM/DER decoding of PKCS8 RSA private keys are 80 times slower in 3.0 · Issue #15199 · openssl/openssl|website=GitHub|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208060652/https://github.com/openssl/openssl/issues/15199|url-status=live}}</ref> The OpenSSL team has created a meta-issue to try to centralize reports of such massive performance regressions.<ref>{{Cite web|url=https://github.com/openssl/openssl/issues/17627|title=3.0 Performance problems · Issue #17627 · openssl/openssl|website=GitHub|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208073139/https://github.com/openssl/openssl/issues/17627|url-status=live}}</ref> About half of these reporters indicate the impossibility for them to upgrade to 3.0 from earlier versions, adding to the trouble caused by the limited support time left on previous version 1.1.1.

=== Consideration for users' requirements ===

While the [[QUIC]] transport layer was being worked on to support the third version of the [[HTTP]] protocol, it was proposed to use TLS to provide security,<ref>{{Cite web |url=https://datatracker.ietf.org/doc/draft-ietf-quic-tls/01/ |title=Using Transport Layer Security (TLS) to Secure QUIC |date=January 14, 2017 |via=IETF |last1=Thomson |first1=Martin |last2=Turner |first2=Sean |access-date=November 27, 2023 |archive-date=December 8, 2024 |archive-url=https://web.archive.org/web/20241208103639/https://datatracker.ietf.org/doc/draft-ietf-quic-tls/01/ |url-status=live}}</ref> and identified that some adaptations to TLS libraries would be needed. Such modifications were brought to BoringSSL<ref>{{Cite web|url=https://bugs.chromium.org/p/boringssl/issues/detail?id=221|title=221 - boringssl - A fork of OpenSSL that is designed to meet Google's needs - Monorail|website=bugs.chromium.org}}</ref> which was the library being primarily used by QUIC developers by then, and later ported to other libraries.<ref>{{Cite web|url=https://gitlab.com/gnutls/gnutls/-/issues/826|title=Support QUIC TLS API (#826) · Issues · gnutls / GnuTLS · GitLab|website=GitLab|date=September 4, 2019|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208020918/https://gitlab.com/gnutls/gnutls/-/issues/826|url-status=live}}</ref> A port of this work was quickly proposed to OpenSSL.<ref name="auto1">{{Cite web|url=https://github.com/openssl/openssl/pull/8797|title=WIP: master QUIC support by tmshort · Pull Request #8797 · openssl/openssl|website=GitHub|access-date=February 25, 2023|archive-date=January 21, 2025|archive-url=https://web.archive.org/web/20250121132358/https://github.com/openssl/openssl/pull/8797|url-status=live}}</ref> While some discussion started the same day, it quickly stalled and was first blocked on license considerations,<ref name="auto1"/> then kept on hold once these concerns were cleared. Finally 10 months later the OpenSSL Management Committee announced on a blog post<ref>{{Cite web |url=https://openssl-library.org/post/2020-02-13-quic-and-openssl/ |title=QUIC and OpenSSL |website=OpenSSL Blog |date=February 17, 2020 |access-date=2024-10-11}}</ref> that this patch set would not be adopted for 3.0 on the fear that the API would change over time. Finally more than one year after planned release of 3.0 which was still not coming, a team of volunteers from [[Akamai]] and [[Microsoft]] decided to fork the project as QuicTLS<ref>{{Cite web|url=https://twitter.com/richsalz/status/1367349918671773697|title=quictls announce on twitter}}</ref> and support these patches on top of the OpenSSL code in order to unblock QUIC development. This action was generally welcome by the community. Finally after OpenSSL 3.0 was finally released, the QUIC patch set was reconsidered and decided against,<ref>{{Cite web|url=https://www.mail-archive.com/openssl-project@openssl.org/msg02585.html|title=OMC Release Requirements|website=www.mail-archive.com|access-date=February 25, 2023|archive-date=January 21, 2025|archive-url=https://web.archive.org/web/20250121112325/https://www.mail-archive.com/openssl-project@openssl.org/msg02585.html|url-status=live}}</ref> causing tens to hundreds of reactions of disappointment among the community.<ref name="auto1"/> The pull request was closed, while users felt the need to publicly express their disappointment,<ref>{{Cite web|url=https://daniel.haxx.se/blog/2021/10/25/the-quic-api-openssl-will-not-provide/|title=The QUIC API OpenSSL will not provide &#124; daniel.haxx.se|date=October 25, 2021|access-date=February 25, 2023|archive-date=January 21, 2025|archive-url=https://web.archive.org/web/20250121161711/https://daniel.haxx.se/blog/2021/10/25/the-quic-api-openssl-will-not-provide/|url-status=live}}</ref> or beg operating system vendors to support the alternative QuicTLS fork,<ref>{{Cite web|url=https://alioth-lists.debian.net/pipermail/pkg-openssl-devel/2021-October/007668.html|title=[Pkg-openssl-devel] Any intent to maintain quictls ?|first=Willy|last=Tarreau|date=October 27, 2021|access-date=February 25, 2023|archive-date=December 7, 2024|archive-url=https://web.archive.org/web/20241207235221/https://alioth-lists.debian.net/pipermail/pkg-openssl-devel/2021-October/007668.html|url-status=live}}</ref><ref>{{Cite web|url=https://groups.google.com/g/linux.debian.bugs.dist/c/CAh0KLP5Euo?pli=1|title=Bug#1011391: openssl: please support quictls patchset|website=groups.google.com|access-date=February 25, 2023|archive-date=December 8, 2024|archive-url=https://web.archive.org/web/20241208091707/https://groups.google.com/g/linux.debian.bugs.dist/c/CAh0KLP5Euo%3Fpli=1|url-status=live}}</ref> or seek for alternative solutions.<ref name="auto2">{{Cite web|url=https://github.com/haproxy/haproxy/issues/680|title=HTTP/3 support · Issue #680 · haproxy/haproxy|website=GitHub|access-date=February 25, 2023|archive-date=December 7, 2024|archive-url=https://web.archive.org/web/20241207220516/https://github.com/haproxy/haproxy/issues/680|url-status=live}}</ref> Finally Rich Salz, co-founder of the QuicTLS fork, announced<ref name="auto2"/> his interest in seeing an Apache project forked from QuicTLS. As of 25 February 2023 there is still no QUIC-compatible long-term supported TLS library available by default in operating systems without requiring end-users to rebuild it themselves from sources.

== See also ==

{{Portal|Free and open-source software}}
* [[Comparison of TLS implementations]]
* [[Comparison of cryptography libraries]]
*[[List of free and open-source software packages]]
* [[POSSE project]]
* [[LibreSSL]]
* [[wolfSSL]]

==Notes==
{{reflist|group=note}}

== References ==

{{Reflist|}}

== External links ==
{{Commons category}}
* {{Official website|https://www.openssl.org/}}
* [https://www.openssl.org/docs/manpages.html OpenSSL Manpages]
* [http://h30266.www3.hpe.com/odl/i64os/opsys/vmsos84/BA554_90007/ch04s03.html OpenSSL Programming Guide] ([https://web.archive.org/web/20201204205634/http://h30266.www3.hpe.com/odl/i64os/opsys/vmsos84/BA554_90007/ch04s03.html archived])
* [https://people.gnome.org/~markmc/openssl-and-the-gpl.html The OpenSSL License and the GPL] {{Webarchive|url=https://web.archive.org/web/20140723105732/https://people.gnome.org/~markmc/openssl-and-the-gpl.html |date=July 23, 2014 }} by Mark McLoughlin
* {{cite web|url=https://developer.ibm.com/technologies/security/tutorials/l-openssl/|title=OpenSSL programming tutorial|date=16 August 2018|archive-url=https://web.archive.org/web/20210510014422/https://developer.ibm.com/technologies/security/tutorials/l-openssl/|archive-date=10 May 2021}}
* [https://wiki.openssl.org/index.php/Main_Page OpenSSL Community Wiki]

{{Cryptographic software}}
{{SSL/TLS}}

{{DEFAULTSORT:Openssl}}
[[Category:Public key infrastructure]]
[[Category:1998 software]]
[[Category:C (programming language) libraries]]
[[Category:Cryptographic software]]
[[Category:Free security software]]
[[Category:Transport Layer Security implementation]]
[[Category:Free software programmed in C]]